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POPULAR SCIENCE MONTHLY 



shoda, which was most carefully planned 

 and took place in a climate that is ex- 

 ceptionallj- dry and hygienic, there was 

 no abatement of typhoid fever. In the 

 case of an outbreak of malignant dysen- 

 tery described by the author in a pre- 

 vious paper, taken at its height, not a 

 new case occurred after measures were 

 adopted that made conveyance by flies 

 impossible, although there had been 

 fresh ones every day for some time pre- 

 viously. Another more recent " lively 

 epidemic " of typhoid mentioned by the 

 author was ended in a day by measures 

 directed against conveyance by water. 

 " When flies are responsible, there are 

 little neighborhood epidemics, extending 

 in short leaps from house to house, with- 

 out reference to water supply or any- 

 thing else in common. But when water 

 is at fault the disease follows its use 

 wherever it may go. . . . Epidemics 

 spread by flies tend to follow the direc- 

 tion of prevailing warm winds, as though 

 the fly, wandering outdoors after con- 

 tact with the source of infection, had 

 drifted with the wind, but nothing of 

 the sort is perceptible in the case of 

 water-borne disease." 



Pottery Making and Lead Poison- 

 ing. — The report of Professors Thorpe 

 and Oliver on the subject of the employ- 

 ment of compounds of lead in the manu- 

 facture of pottery, especially in its rela- 

 tion to the health of the work people, has 

 just been issued as an English blue book. 

 It appears that of the total male workers 

 in the year 1898, 4.9 per cent became 

 " leaded," while of the female workers 

 the proportion was 12.4 per cent. It is 

 stated that in the last six months many 

 successful attempts have been made by 

 the manufacturers to substitute a lead- 

 less glaze, and there seems no doubt 

 that glazes of sufficient brilliancy, cov- 

 ering power, and durability are now 

 within the reach of the manufacturer. 

 The exclusion of women from certain 

 parts of the work, except where lead- 

 less glazes are used, is advocated, and 

 also various expedients for preventing 

 the absorption of tlie lead by the skin, 

 such as rubber gloves or " dipping " 

 tongs. Their general conclusions are 

 as follows: "That by far the greater 

 amount of earthenware of the class al- 

 ready specified can be glazed without 

 the use of lead in any form. It has 



been demonstrated, without the slight- 

 est doubt, that the ware so made is in 

 no respects inferior to that coated Avith 

 lead glaze. There seems no reason, 

 therefore, why in the manufacture of 

 this class of goods the operatives should 

 still continue to be exposed to the evils 

 which the use of lead glaze entails. 

 There are, however, certain branches 

 of the pottery industry in which it 

 would be more difficult to dispense with 

 the use of lead compounds. But there 

 is no reason why, in these cases, the 

 lead so employed should not be in the 

 form of a fritted double silicate. Such 

 a compound, if properly made, is but 

 slightly attacked by even strong hydro- 

 chloric, acetic, or lactic acid. There can 

 be little doubt that, if lead must be used, 

 the employment of such a compound sili- 

 cate — if its use could be insured — would 

 greatly diminish the evil of lead poison- 

 ing. The use of raw lead as an ingredient 

 of glazing material, or as an ingredient 

 of colors which have to be subsequently 

 fired, should be absolutely prohibited. 

 As it would be very difficult to insure 

 that an innocuous lead glaze shall be 

 employed, we are of opinion that young 

 persons and women should be excluded 

 fi-om employment as dippers, dippers' 

 assistants, ware cleaners after dippers, 

 and glost placers in factories where lead 

 glaze is used, and that the adult male 

 clippers, dippers' assistants, ware clean- 

 ers, and glost placers should be sub- 

 jected to systematic medical inspection. 

 In the 1893 report the medical members 

 of the committee expressed the opinion 

 that ' many old factories are wholly, or 

 in part, unfit in a sanitary point of view 

 for occupation,' and they suggested that 

 ' there should be some authority to 

 close them, or whatever part of them 

 is condemned, on the same principle as 

 dwellings are declared uninhabitable.' 

 We share this opinion and we concur in 

 the suggestion. Certain of the factories 

 we have inspected are in the last stages 

 of dilapidation, and it appears to us 

 to be well-nigh impossible to introduce 

 into them such rearrangements or addi- 

 tions as are required by the amended 

 special rules." 



The Longevity of Animals. — The 



following intorcsting table, showing the 

 periods of maturity and the full term of 

 life of various animals, was prepared by 



